Hoists are commonly supported in a suspended manner with a fixed mounting or a swivel mounting. Fixed mounting arrangements are preferred due to their simplicity and because the mounting height of a fixed arrangement is smaller than that of swivel mounting arrangements. However, fixed mountings cannot be used in all applications and swivel mountings must be used in some situations irrespective of their complexity and excessive mounting height. Swivel mountings are required in those cases where two mounting supports are needed for one hoist and the hoist is mounted on a trolley which travels on a curved beam or similar guide track support. Swivel mountings are also needed in those situations where the load must be rotated in its handling or transporting or where the load swings or moves such that bending stress is applied to the mounting mechanism. In general, swivel mountings are required in applications where flexibility between the hoist and its supporting apparatus, such as a trolley, is required.
A typical swivel mounting apparatus includes an attachment lug on the top of a hoist frame and a supporting yoke affixed to the bottom portion of a trolley from which the hoist is suspended. A second yoke member may be positioned between the trolley yoke and the hoist top lug and bolted to the hoist top lug in a manner permitting pivoting motion of the hoist relative to the trolley about a single horizontal axis. A bolt is extended through the trolley yoke and the second yoke member and has a nut at its bottom end which retains the hoist on the trolley. The bolt passes through thrust bushings which engage the trolley yoke and the second yoke member and permit the pivoting movement about the vertical axis. Thus, this type of swivel mounting permits a swivel motion of the hoist relative to the trolley due to the horizontal and vertical pivoting motion provided by the swivel mounting. As may be appreciated, such a swivel mounting is fairly complex and occupies a substantial mounting height due to the various mounting lugs, yoke members, and bolts and bushings required to provide the support in a swivelable manner.